ICD-10 Code D47.0 – Mast cell neoplasms of uncertain behavior (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code D47.0 – Mast cell neoplasms of uncertain behavior
What it is
D47.0 identifies a mast cell neoplasm whose behavior is uncertain, meaning the record does not support a clearly benign or malignant classification. Use it for documented mast cell proliferations when the clinician has not assigned a more specific diagnosis.
Clinical signs
Clinical features vary; refer to documentation. Mast cell disorders may present with skin findings, flushing, itching, or other signs of mast cell activation, but the exact pattern depends on the type and site of disease.
When to use this code
Use D47.0 when the provider documents a mast cell neoplasm or mast cell proliferation of uncertain behavior and no more specific code is available. It may also fit when pathology or the assessment describes uncertain biologic behavior. Code only what is explicitly documented.
Do not use for
Do not use this code for clearly benign or malignant mast cell disease when a more specific diagnosis is documented. Check documentation if the record instead describes a different hematologic disorder or a non-neoplastic mast cell condition.
Coding tip
Verify the wording in pathology and the final assessment, because “uncertain behavior” must be supported by the provider’s documentation.